Pontiac FIREBIRD 1972 Service Manual page 325

SECTION 4 A
NON TYPE C DIFFERENTIAL
The following caution applies to one or more steps in the assembly proce-
dure of components in this portion of the manual as indicated at appropri-
ate locations by the terminology "See Caution on page 1 of this Section".
CAUTION: TUIS FASTENER IS A N IMPORTANT ATTACHING
PART IN THAT IT COULD AFFECT THE PERFORMANCE OF
VITAL COMPONENTS AND SYSTEMS, AND/OR COULD RE-
SULT IN MAJOR REPAIR EXPENSE. IT MUST BE REPLACED
WITH ONE OF THE SAME PART NUMBER OR WITH A N
EQUIVALENT PART IF REPLACEMENT BECOMES NECES-
SAR Y. DO NOT USE A REPLACEMENTPAR T OFLESSER QUAL-
ITY OR SUBSTITUTE DESIGN. TORQUE VALUES MUST BE
USED AS SPECIFIED DURING REASSEMBL Y TO ASSURE
PROPER RETENTION OF THIS PAR T
CONTENTS OF THIS SECTION
Trouble Diagnosis and Testing
..............................
4A-1
Gear Tooth Nomenclature
......................................
4A-5
Red Lead Test
........................................................
4A-5
Adjustments Affecting Tooth Contact
..................
4A-5
General Description
................................................
4A-7
Design
.....................................................................
4A-8
Operation
............................................................
4A-8
Axle Ratios
...........................................................
4A-9
Periodic Service
.....................................................
4A- 11
Minor Service
........................................................
4A- 1 1
Remove Companion Flange
..............................
4A- 11
....................................
Pinion Bearing Oil Seal 4A-12
Axle Shaft
........................................................
4A- 13
......................................................
Axle Bearing 4A- 13
................................................
Rear Wheel Stud 4A- 15
Axle Seal
............................................................
4A- 13
........................................................
Install Axle 4A-16
........................................................
Major Service 4A- 16
........................................
Overhaul Differential 4A- 16
Setting Pinion Depth
........................................
4A-22
Adjust Side Bearing Pre-Load
..........................
4A-25
................................................
Adjust Backlash 4A-26
TROUBLE DIAGNOSIS AND TESTING
Many noises reported as coming from the rear axle actu-
ally originate from other sources such as tires, road sur-
faces, wheel bearings, engine, transmission, mumer or
body drumming. A thorough and careful check should be
made to determine the source of the noise before disassem-
bling the differential. Noise which originates in other
places cannot be corrected by adjustment or replacement
of parts in the rear axle. It should also be remembered that
differential gears, like any other mechanical device, are
not absolutely quiet and should be accepted as being com-
mercially quiet unless some abnormal noise is present.
To make a systematic check for axle noise under standard
conditions, observe the following:
2. Drive car far enough to thoroughly warm up rear
axle lubricant.
3. Note speed at which noise occurs. Then stop car and,
with clutch disengaged or automatic transmission in
neutral, run engine slowly up and down through en-
gine speeds, corresponding to car speed at which
noise was most pronounced, to determine if it is
caused by exhaust, mumer roar or other engine con-
ditions. Repeat, while engaging and disengaging
clutch (transmission in neutral), to determine if noise
is in transmission. (Transmission rear bearing noise
can only be isolated by removing propeller shaft and
operating transmission in high.)
1. Select a smooth, level tarvia or asphalt road to reduce 4. Tire noise changes with different road surfaces, but
tire noise and body drumming. rear axle noise does not. Temporarily inflating all